This invention relates to a coated article including at least one diamond-like carbon (DLC) inclusive layer and at least one layer deposited using a siloxane and/or oxygen (O) inclusive organosilicon compound gas (e.g., hexamethyldisiloxane gas which may be abbreviated herein as HMDSO) provided on (directly or indirectly) a substrate of glass, plastic, ceramic, or the like, and a corresponding method of making the same.
It is known to deposit diamond-like carbon (DLC) coatings on a substrate. Unfortunately, DLC becomes dark in color and absorbs visible light rays at high thicknesses. DLC may even absorb some visible light at small thicknesses.
There exists a need in the art to coat articles such as vehicle windows/windshields, architectural glass, etc. with DLC in order to make such articles more scratch resistant and durable. However, such articles may often be used in environments (e.g., vehicle windshields, vehicle windows, etc.) where high visible light transmission (i.e., low visible light reflection and/or absorption) is desirable. Thus, there exists a need in the art to provide a coated article including at least one DLC inclusive layer(s) thereon for durability purposes which at the same time can experience sufficiently high visible light transmittance and/or low visible light reflectance if same is desired.
Certain of the aforesaid parent applications discuss the use of a TMS gas to form a DLC inclusive layer disposed between a glass substrate and another DLC inclusive layer deposited via at least acetylene gas. While such articles have many desirable characteristics and function very well, the use of TMS gas to form the layer between the other DLC inclusive layer and a glass substrate has been found to lead to a resulting article experiencing more visible light reflection than would otherwise be desired. The refractive index xe2x80x9cnxe2x80x9d of glass is about 1.57, while the refractive index xe2x80x9cnxe2x80x9d of DLC deposited via acetylene gas is about 2.0 in the visible range. A layer deposited using TMS gas typically has a refractive index xe2x80x9cnxe2x80x9d of about 1.9 to 2.0. As a result of the rather high refractive index xe2x80x9cnxe2x80x9d of such a TMS layer, the resulting article tends to experience more visible light reflection than would otherwise be desired in certain circumstances.
In view of the above, it is apparent that there exists a need in the art for a coated article including at least one DLC inclusive layer that has good visible transmission characteristics, and a corresponding method of making the same. There also exists a need in the art for a layer which can be deposited directly between a glass substrate and a DLC inclusive layer that more closely matches or couples the respective refractive indices of the glass and DLC in order to reduce visible reflection(s) off of the resulting coated article. Thus, there further exists a need in the art for a layer having a refractive index xe2x80x9cnxe2x80x9d of from about 1.4 to 2.0 (more preferably from about 1.5 to 1.8) that is compatible with DLC and glass which may be disposed between a DLC inclusive layer and a glass substrate, which can limit visible light reflection off of a resulting coated article and simultaneously can provide a good bond between the DLC and glass.
It has also been found that under certain circumstances hydrophobic layers such as fluoro-alkyl silane (FAS) inclusive layers have trouble bonding directly to hard DLC inclusive layers deposited using acetylene gas. Thus, there also exists a need in the art for a DLC inclusive hydrophobic coating system including a primer layer for improving bonding between an overlying hydrophobic layer and an underlying DLC inclusive layer.
It is a purpose of different embodiments of this invention to fulfill any and/or all of the above described needs in the art, and/or other needs which will become apparent to the skilled artisan once given the following disclosure.
In certain embodiments of this invention, a coated article includes an oxygen (O) and/or silicon (Si) inclusive anti-reflection layer disposed between a glass substrate and a diamond-like carbon (DLC) inclusive layer. The presence of oxygen and/or silicon in the anti-reflective layer tends to lower the refractive index xe2x80x9cnxe2x80x9d (visible) so as to be within the range of from about 1.4 to 2.0 (more preferably from about 1.5 to 1.9, and most preferably from about 1.5 to 1.8), and also enables good bonding with both the DLC inclusive layer(s) and the glass substrate. The anti-reflective index xe2x80x9cnxe2x80x9d (visible) matching/coupling layer enables visible reflection off of the resulting coated article to be reduced. In certain exemplary embodiments, the anti-reflective and/or index matching/coupling layer may include at least some DLC to improve bonding and/or durability characteristics of the resulting coated article.
According to an exemplary method of making such a coated article, at least a siloxane gas (e.g., HMDSO, OMCTSO, TMDSO, TEOS, etc.) is utilized in order to deposit the anti-reflective layer(s). According to certain embodiments, at least an oxygen (O) inclusive organosilicon (this phrase including siloxanes and other oxygen inclusive organosilicon compounds) compound inclusive gas may be used to deposit the antireflective layer(s).
In certain embodiments, an oxide inclusive primer layer(s) may be provided over the DLC inclusive layer(s) and a hydrophobic layer (e.g., FAS inclusive layer) may be provided over the primer layer(s). The primer layer(s) may include or be of, for example, any of the aforesaid materials that may be used for the index matching layer and thus may be DLC inclusive in certain embodiments. Alternatively, the primer layer(s) may instead be of or include an oxide such as titanium oxide (TiOx), silicon oxide (SiOx), HfOx, VOx, any combination thereof, or any other suitable oxide material having any desired stoichiometry.
Coated articles made according to certain embodiments of this invention may be hydrophobic (e.g., shed water), while coated articles made according to other embodiments of this invention need not be hydrophobic. In hydrophobic embodiments, an object of this invention is to provide a durable coated article that can shed or repel water (e.g. automotive windshield, automotive backlite, automotive side window, architectural window, bathroom shower glass, residential window, bathroom shower door, coated ceramic article/tile, etc.). In one exemplary hydrophobic embodiment, a coating system includes each of DLC and FAS, the DLC being provided for at least durability purposes and the FAS for increasing the contact angle of the coating system.
In certain embodiments of this invention, an object of this invention is to provide a coated substrate having a coating system including sp3 carbon-carbon bonds and an adhesion energy (or wettability) W with regard to water of less than or equal to about 23 mN/m, more preferably less than or equal to about 21 mN/m, even more preferably less than or equal to about 20 mN/m, and in most preferred embodiments less than or equal to about 19 mN/meter in order to provide hydrophobicity. This can also be explained or measured in energy per unit area (mJ/m2). Another exemplary object is to provide a coating system having a surface energy xcex3c (on the surface of the coated article) of less than or equal to about 20.2 mN/m, more preferably less than or equal to about 19.5 mN/m, and most preferably less than or equal to about 18 mN/m in order to provide hydrophobicity.
In hydrophobic embodiments, an object of this invention is to provide a coated substrate, wherein a DLC inclusive coating system has an initial (i.e. prior to being exposed to environmental tests, rubbing tests, acid tests, UV tests, or the like) water contact angle xcex8 of at least about 80 degrees, more preferably of at least about 100 degrees, even more preferably of at least about 110 degrees, and most preferably of at least about 125 degrees.
Another object of this invention is to manufacture a coated article wherein the temperature of an underlying glass substrate may be less than about 200xc2x0 C., preferably less than about 150xc2x0 C., most preferably less than about 80xc2x0 C., during the deposition of a DLC inclusive coating system. This reduces graphitization during the deposition process, as well as reduces detempering and/or damage to low-E and/or IR-reflective coatings already on the substrate in certain embodiments.
Yet another object of this invention is to fulfill any and/or all of the aforesaid objects and/or needs.
This invention will now be described with respect to certain embodiments thereof, along with reference to the accompanying illustrations.